1. Field of the Invention
The present invention relates to a video signal delay circuit, used in a television receiver or a video tape recorder, for delaying a delay signal by a predetermined period of time by, e.g., a charge coupled device-type delay element (to be referred to as a CCD delay element hereinafter) and, more particularly, to a video signal delay circuit capable of compensating for attenuation of a signal that has passed through a CCD delay element.
2. Description of the Related Art
A video signal delay circuit is used in a television receiver in order to delay a television video signal for one horizontal period. A conventional video signal delay circuit comprises a CCD deay element and an amplifier. More specifically, a video signal is supplied directly to the CCD delay element and is delayed by it for one horizontal period. The video signal delayed by the CCD delay element is supplied to the amplifier, and attenuation caused by the CCD delay element is compensated for by the amplifier. As an amplifier of this type, one having a constant gain is conventionally used.
An attenuation amount of a video signal caused by a CCD delay element varies depending on a manufacturing error of the CCD delay element, a change in operating condition of the element, and the like and is thus not constant. Therefore, when a video signal output from the CCD delay element is amplified using an amplifier having a constant gain, the gain of the overall video signal delay circuit is not constant.
It is an object of the present invention to provide a video signal delay circuit which can stabilize, when a video signal is delayed by a semiconductor delay element such as a CCD delay element, the gain of the overall video signal delay circuit even if the attenuation amount of the video signal fluctuates due to the manufacturing error of the semiconductor delay element or the change in operating condition of the element.